The present invention relates to the installation of cardiac stimulation probes intended to be implanted in the coronary network of the heart to allow the stimulation of a left heart cavity by an xe2x80x9cactive implantable medical devicexe2x80x9d, as such devices are defined by the Jun. 20, 1990 directive 90/385/CEE of the Council of the European Communities, and particularly a device such as a pacemaker, a defibrillator and/or a cardiovertor, and more particularly a pacemaker of the xe2x80x9cmultisitexe2x80x9d type.
The publication EP-A-0 993 840 and its corresponding U.S. patent application Ser. No. 09/416,140, which are commonly owned by the Assignee hereof, Ela Medical, describes a probe to be implanted in the coronary sinus network that is designed according to a number of precise criteria, in particular, criteria relating to the geometry and the flexibility of the distal part of the probe. U.S. application Ser. No. 09/416,140 is hereby incorporated herein by reference for the entirety of its disclosure.
Such a probe is not an endocavitary probe (such as are the probes for stimulating right heart cavities), but rather a probe to be introduced into the coronary network, to present an electrode disposed facing the left ventricle. Similarly, stimulation of the left atrium can be obtained by the choice of a different suitable stimulation site.
The access to the entry of the coronary sinus network is via the right atrium. The introduction of a probe through an endocavitary path is, however, a particularly delicate intervention. This is due to the fact that the position of the stimulation point (i.e., where the electrode contacts the tissue) is very important in the case of a xe2x80x9cmultisitexe2x80x9d type pacemaker, where the left ventricle and right ventricle stimulation sites have to be spaced as far apart as possible to optimize the resynchronization of all of the cardiac cavities.
One of the techniques known for installing such a probe uses an accessory called a xe2x80x9cguiding catheterxe2x80x9d as described, for example, in the PCT publication WO-A99/55412. A guiding catheter is typically a hollow tube or sheath reinforced by a wire mesh, having an interior lumen with a surface that has a low coefficient of friction (for example, a surface of PTFE co-extruded or co-molded with the remainder of the sheath). The tube also has a flexibility that is selected so as to have a sufficient rigidity in torsion, to allow the transmission of a rotational movement imparted at one end to the other end, in order to be able to adjust the orientation of the extremity of the probe against the myocardium during installation of the probe.
In addition, the guiding catheter is typically of the xe2x80x9csoft tipxe2x80x9d type, i e in its terminal region, its flexibility increases as one approaches the distal end. This variation in flexibility is provided to allow an atraumatic approach of the guiding catheter in the coronary network and to cross obstacles such as valvules without too many difficulties and without wounding tissue.
Once installed in place, the guiding catheter constitutes a direct xe2x80x9ctunnelxe2x80x9d between the xe2x80x9cexternal worldxe2x80x9d and the coronary sinus, that the surgeon can then use to slide the probe through until the probe reaches the final position. At this stage, an important difficulty arises with respect to the withdrawal of the guiding catheter. The guiding catheter withdrawal must of course be operated without dislodging or modifying the orientation of the installed probe.
Until now, at the time of its withdrawal, the guiding catheter has typically been cut at its proximal end near the generator by means of a cutting tool, located on the terminal extremity. The cutting tool is used to split both the end-handle of the guiding catheter and the wire mesh forming the reinforcement of the hollow tube. This technique of cutting the sheath away from the guiding catheter after installation of the probe presents a risk of damaging the probe because of the proximity of the cutting tool to the body of the probe, i.e., short distance of about 1 mm.
Installation kits of a different structure have been proposed to cure this disadvantage, with, for example, a sheath that is peelable, but not reinforced. Unfortunately, the pre-cutting of the sheath along its length to make it peelable also results in a weakness and a lesser rigidity of the tube, with a risk of the tube folding or collapsing, and a less effective transmission of the effort exerted at the proximal end at the time of the implantation.
Thus, there is a continuing need for a satisfactory solution to the problem of withdrawal of the guiding catheter, a process which still remains extremely dependent on the dexterity of the surgeon and the usual risks of a complex intervention of this nature.
It is, therefore, an object of the present invention to propose an installation kit for a coronary sinus probe that mitigates the above-mentioned difficulties by allowing an easy and sure withdrawal of the guiding catheter, yet is freed from a dependency on the degree of dexterity of the operator.
Broadly, the installation kit of the present invention includes a guiding catheter and an extension. The guiding catheter is of a type in itself known, i.e., comprising an internal lumen open at its two ends and able to receive the probe along its length. The guiding catheter also is preferably provided with a sufficient torsional rigidity to allow the transmission of a rotational movement imparted at one extremity to the other extremity, and it also has a so-called soft tip, that is an increased flexibility in the vicinity of its distal extremity.
The extension comprises a member having a proximal extremity, a distal extremity, an internal lumen open at its two ends, and a connector element at its distal extremity that mounts to the proximal extremity of the probe. The probe proximal extremity is provided with a length having a uniform diameter (xe2x80x9cmonodiameterxe2x80x9d). The extension connector has an external diameter that is substantially the same as the diameter of the remainder of the extension. The extension has an external surface that has a low coefficient of friction as compared to the interior surface of the lumen of the guiding catheter. The external diameter of the extension is smaller than the interior diameter of the lumen of the guiding catheter, so as to allow an axial slip of the guiding catheter along the entire length of the extension (including the extension connector), without a concomitant axial displacement of the probe.
Advantageously, in preferred embodiments, the present invention is variously directed to an installation kit also including one or more of the following elements:
(1) a long stylet, able to be inserted in an internal lumen of the extension at a proximal extremity, the length of the long stylet being greater than the sum of the lengths of the probe and the extension;
(2) a sleeve, able to be fitted on the monodiameter proximal extremity of the probe, so as to form an electric connection plug connectable to a connector head of a pacemaker or defibrillator, preferably in conformity with the system connection standard IS-1;
(3) a short stylet, able to be inserted jointly in the sleeve and an internal lumen of the probe at the proximal extremity of the probe; and
(4) a tool comprising a distal housing able to receive the short stylet and also be threaded on the monodiameter proximal extremity of the probe; this tool more preferably also including a depth gauge for use in adjusting the axial penetration depth of the sleeve relative to the monodiameter proximal extremity of the probe.
The invention also is directed to a method of installing a coronary sinus probe using the kit(s) described herein.